U.S. patent number 9,562,942 [Application Number 14/328,860] was granted by the patent office on 2017-02-07 for probe apparatus.
This patent grant is currently assigned to TOKYO ELECTRON LIMITED. The grantee listed for this patent is Tokyo Electron Limited. Invention is credited to Masataka Hatta, Eiichi Shinohara, Kenji Yamaguchi.
United States Patent |
9,562,942 |
Shinohara , et al. |
February 7, 2017 |
**Please see images for:
( Certificate of Correction ) ** |
Probe apparatus
Abstract
A probe apparatus can suppress a spark from occurring near a
wafer surface simply and efficiently when inspecting electrical
characteristics of a semiconductor device at wafer level. A spark
preventing device 50 mounted in the probe apparatus includes a
surrounding member 52 which surrounds probe needles 24G and 24S
between a probe card 16 and a mounting table 12; and a gas supply
device 54 configured to supply a gas to a vicinity of the probe
needles 24G and 24S through an inside or a vicinity of the
surrounding member 52 to form an atmosphere of a preset pressure
higher than an atmospheric pressure in the vicinity of the probe
needles 24G and 24S when inspecting the electrical characteristics
of each chip on a semiconductor wafer W. A contact plate 34 also
serves as the surrounding member 52.
Inventors: |
Shinohara; Eiichi (Nirasaki,
JP), Yamaguchi; Kenji (Tokyo, JP), Hatta;
Masataka (Nirasaki, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Tokyo |
N/A |
JP |
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|
Assignee: |
TOKYO ELECTRON LIMITED (Tokyo,
JP)
|
Family
ID: |
51225275 |
Appl.
No.: |
14/328,860 |
Filed: |
July 11, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150015285 A1 |
Jan 15, 2015 |
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Foreign Application Priority Data
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Jul 11, 2013 [JP] |
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2013-145598 |
Mar 27, 2014 [JP] |
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2014-065736 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R
31/31905 (20130101); G01R 31/2601 (20130101); G01R
1/0491 (20130101); G01R 1/067 (20130101); G01R
31/2879 (20130101); G01R 31/2862 (20130101) |
Current International
Class: |
G01R
31/26 (20140101); G01R 1/04 (20060101); G01R
31/28 (20060101); G01R 1/067 (20060101); G01R
31/319 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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412175 |
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Oct 2004 |
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AT |
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2003-100819 |
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Apr 2003 |
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JP |
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2010/021070 |
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Feb 2010 |
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WO |
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2012/122578 |
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Sep 2012 |
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WO |
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Primary Examiner: Le; Son
Assistant Examiner: Ferdous; Zannatul
Attorney, Agent or Firm: Pearne & Gordon LLP
Claims
We claim:
1. A probe apparatus of inspecting an electrical characteristic of
a semiconductor device formed on a semiconductor wafer, the probe
apparatus comprising: a movable mounting table configured to mount
and support the semiconductor wafer thereon; a probe card that is
provided above the mounting table to face the mounting table, and
is configured to support a probe needle having a leading end to be
come into contact with an electrode on the semiconductor wafer
supported on the mounting table; a surrounding member comprising at
least one contact plate that is provided between the probe card and
the mounting table and configured to surround the probe needle; and
a gas supply device configured to supply a gas into a surrounding
space confined by the mounting table, the probe card and the
surrounding member through an inside or a vicinity of the
surrounding member in order to form an atmosphere of a pressure
higher than an atmospheric pressure in the vicinity of the probe
needle when inspecting the electrical characteristic of the
semiconductor device, wherein the surrounding member includes gas
discharge openings at an inner peripheral surface of the
surrounding member, and the gas is discharged from the gas
discharge openings and supplied into the surrounding space.
2. The probe apparatus of claim 1, wherein the gas supply device
comprises a gas supply line passing through a vicinity of the probe
card.
3. The probe apparatus of claim 1, wherein a labyrinth seal is
provided on a bottom surface of the surrounding member.
4. The probe apparatus of claim 3, wherein the labyrinth seal
comprises multiple concentric labyrinth fins surrounding the
leading end of the probe needle.
5. The probe apparatus of claim 3, wherein the labyrinth seal is
provided adjacent to the inner peripheral surface of the
surrounding member facing the probe needle.
6. The probe apparatus of claim 3, wherein the labyrinth seal is
provided on a bottom surface of a partition wall protruded from the
bottom surface of the surrounding member.
7. The probe apparatus of claim 1, wherein a seal ring surrounding
the semiconductor wafer is provided on the mounting table.
8. The probe apparatus of claim 7, wherein the seal ring has a
thickness same as that of the semiconductor wafer on the mounting
table.
9. The probe apparatus of claim 1, wherein a protrusion configured
to surround the probe needle and close a gap between the
surrounding member and the mounting table is provided on the
surrounding member or the mounting table.
10. The probe apparatus of claim 1, further comprising: a gas
collecting unit configured to collect the gas, which is supplied
into the surrounding space by the gas supply device, by a vacuum
attracting force.
11. The probe apparatus of claim 1, wherein the gas supply device
comprises multiple gas supply sources configured to discharge
plural kinds of gases individually, and one of the gas supply
sources is selectively used, and at least one of the gas supply
sources comprises an insulating liquid vaporizing device configured
to generate an insulating gas by vaporizing an insulating liquid
having high voltage resistance.
12. A probe apparatus of inspecting an electrical characteristic of
a power device that is formed on a semiconductor wafer and has
electrodes on front and rear surfaces thereof, the probe apparatus
comprising: a movable mounting table configured to mount and
support the semiconductor wafer thereon; a probe card that is
provided above the mounting table to face the mounting table, and
is configured to support a probe needle having a leading end to be
come into contact with the electrode on the front surface of the
power device, the electrode on the front surface of the power
device being exposed at a front surface of the semiconductor wafer
supported on the mounting table; a first connection conductor
configured to connect the probe needle and a corresponding first
terminal of a tester; a mounting surface conductor that serves as a
mounting surface of the mounting table and is configured to be in
contact with the electrode on the rear surface of the power device,
the electrode on the rear surface of the power device being exposed
at a rear surface of the semiconductor wafer supported on the
mounting table; a contactor that is provided at the mounting table
and is configured to be vertically moved and electrically connected
with the mounting surface conductor; a contact plate, having a
conductivity, provided between the mounting table and the probe
card to come into contact with the contactor at a bottom surface
thereof and configured to surround the probe needle; a second
connection conductor configured to connect the contact plate and a
corresponding second terminal of the tester; and a gas supply
device configured to supply a gas into a surrounding space confined
by the mounting table, the probe card and the contact plate through
an inside or a vicinity of the contact plate in order to form an
atmosphere of a pressure higher than an atmospheric pressure in the
vicinity of the probe needle when inspecting the electrical
characteristic of the power device, wherein the contact plate
includes gas discharge openings at an inner peripheral surface of
the contact plate, and the gas is discharged from the gas discharge
openings and supplied into the surrounding space.
13. The probe apparatus of claim 12, wherein the gas supply device
comprises a gas supply line passing through a vicinity of the probe
card.
14. The probe apparatus of claim 13, wherein the gas supply line is
extended through a probe card holder configured to detachably
support the probe card in the vicinity of the probe card.
15. The probe apparatus of claim 14, wherein a plate top surface
terminal is provided on a top surface of the contact plate and
connected to the second connection conductor, the plate top surface
terminal and the second terminal of the tester face each other in a
vertical direction, and the second connection conductor is
straightly extended through the probe card holder in the vertical
direction.
16. The probe apparatus of claim 15, wherein an upper end of the
second connection conductor is brought into direct contact with the
second terminal of the tester in a detachable manner.
17. The probe apparatus of claim 12, wherein a base end of the
probe needle and the first terminal of the tester face each other
in a vertical direction, and at least a part of the first
connection conductor is straightly extended through the probe card
in the vertical direction.
18. The probe apparatus of claim 17, wherein an upper end of the
first connection conductor is brought into direct contact with the
first terminal of the tester in a detachable manner.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Japanese Patent Application
Nos. 2013-145598 and 2014-065736 filed on Jul. 11, 2013 and Mar.
27, 2014, respectively, the entire disclosures of which are
incorporated herein by reference.
TECHNICAL FIELD
The embodiments described herein pertain generally to a probe
apparatus of inspecting electrical characteristics of a
semiconductor device at wafer level.
BACKGROUND
In a manufacturing process of a semiconductor device, electrical
characteristics of the semiconductor device are inspected by a
semiconductor testing apparatus at the end of a pre-process or a
post-process, so that faults of chips are inspected. In such a
semiconductor testing apparatus, a probe apparatus serves as a
handling apparatus that interfaces the chips on the semiconductor
wafer, and a tester in charge of signal processing when performing
an inspection at wafer state or at wafer level. Typically, the
probe apparatus includes a movable mounting table (chuck top)
configured to mount and support thereon the semiconductor wafer; a
probe card having probe needles to be brought into contact with
electrodes of each chip, thus allowing the chips to be electrically
connected with the tester; and a moving device configured to move
the mounting table to align the inspection target chips with
respect to the probe needles or to the probe card fixed at a
certain position.
A voltage (a breakdown voltage or a rated voltage) treated in a
semiconductor device for power supply, i.e., a so-called power
device, such as a power MOSFET or IGBT may be greatly differed
depending on the purposes of use. For example, the power device may
treat a voltage ranging from about 100 V to about 200 V in
electronic home appliances, whereas the power device may treat a
very high voltage ranging from about 600 V to about 1000 V in cars
or industrial appliances. In railroad vehicles or power
transmission and distribution systems, the power device may treat
several thousands of voltages or higher.
Accordingly, when conducting inspection of electrical
characteristics of a power device at wafer level in the
semiconductor testing device, a voltage suitable for the power
device may be applied from the tester to terminals on individual
inspection target chips (power devices) on a wafer via the probe
needles. If, however, the voltage applied for inspecting the chips
is high, a spark (electric discharge) may be generated in the
vicinity of a surface of the wafer, so that adjacent chips (power
devices) may be damaged. This problem is more conspicuous in a SiC
power device than in a Si power device.
Recently, a SiC power device is attracting attention as a
next-generation power device having a compact size, a high
breakdown voltage and a low loss. Since, however, a chip of the SiC
power device is small-sized, a gap between electrodes on the chip
is narrow, and a spark may be easily generated between a probe
needle that applies a high voltage and a probe needle that applies
a low voltage, or between a high-voltage probe needle and an
electrode on an adjacent chip. Further, since it is difficult to
forma protection circuit within the small-sized chip, the chip is
weak for the spark.
To solve this problem, there is known a breakdown voltage
inspecting apparatus (see, for example, Patent Documents 1 and 2).
In this technique, an entire surface of a semiconductor wafer is
covered with a liquid having higher insulation property than the
atmosphere, or a surface of a inspection target chip is locally
covered with such an insulating liquid on the wafer. Then, a
breakdown voltage test is conducted by bringing a probe needle into
contact with an electrode of the inspection target chip covered
with the insulating liquid.
In such a breakdown voltage inspecting apparatus, since a leading
end of the probe needle comes into contact with the electrode of
the inspection target chip in the insulating liquid, a spark may
not be generated from the probe needle, so that the inspection can
be safely conducted even in a test in which a high voltage equal to
or higher than several thousands of voltages is applied. Patent
Document 1: Japanese Patent Laid-open Publication No. 2003-100819
Patent Document 2: International Publication No. WO2010/021070
However, if the configuration of covering the entire surface of the
semiconductor wafer with the insulating liquid (Patent Document 1)
and the configuration of locally covering only the surface of the
inspection target chip on the wafer (Patent Document 2) are adopted
to an actual breakdown inspecting apparatus or a probe apparatus, a
device or a control device for handling the insulating liquid on
the wafer may be complicated, though the degree of complication may
be differed therebetween. Further, an inspection time may also be
lengthened.
SUMMARY
In view of the foregoing problems, example embodiments provide a
probe apparatus capable of suppressing a spark (electric discharge)
from occurring near a wafer surface simply and efficiently when
inspecting electrical characteristics of a semiconductor device at
wafer level.
In one example embodiment, a probe apparatus of inspecting an
electrical characteristic of a semiconductor device formed on a
semiconductor wafer includes a movable mounting table configured to
mount and support the semiconductor wafer thereon; a probe card
this is provided above the mounting table to face the mounting
table, and is configured to support a probe needle having a leading
end to be come into contact with an electrode on the semiconductor
wafer supported on the mounting table; a surrounding member that is
provided between the probe card and the mounting table and
configured to surround a vicinity of the probe needle; and a gas
supply device configured to supply a gas to the vicinity of the
probe needle through an inside or a vicinity of the surrounding
member in order to form an atmosphere of a pressure higher than an
atmospheric pressure in the vicinity of the probe needle when
inspecting the electrical characteristic of the semiconductor
device.
In the present example embodiment, it may be possible to suppress a
spark from occurring on the surface of the semiconductor wafer
based on Paschen's law by forming the atmosphere of the pressure
higher than the atmospheric pressure in the vicinity of the probe
needles when inspecting the electrical characteristics of the
semiconductor device on the semiconductor wafer. Further, since the
gas atmosphere is formed on the semiconductor wafer in order to
suppress a spark, the configuration and the control thereof may be
simple, without increasing the inspection time.
In another example embodiment, a probe apparatus of inspecting an
electrical characteristic of a power device that is formed on a
semiconductor wafer and has electrodes on a front and rear surfaces
thereof includes a movable mounting table configured to mount and
support the semiconductor wafer thereon; a probe card that is
provided above the mounting table to face the mounting table, and
is configured to support a probe needle having a leading end to be
come into contact with the electrode on the front surface of the
power device, the electrode on the front surface of the power
device being exposed at a front surface of the semiconductor wafer
supported on the mounting table; a first connection conductor
configured to connect the probe needle and a corresponding first
terminal of a tester; a mounting surface conductor that serves as a
mounting surface of the mounting table and is configured to be in
contact with the electrode on the rear surface of the power device,
the electrode on the rear surface of the power device being exposed
at a rear surface of the semiconductor wafer supported on the
mounting table; a contactor that is provided at the mounting table
and is configured to be vertically moved and electrically connected
with the mounting surface conductor; a contact plate, having a
conductivity, provided between the mounting table and the probe
card to come into contact with the contactor at a bottom surface
thereof and configured to surround the probe needle; a second
connection conductor configured to connect the contact plate and a
corresponding second terminal of the tester; and a gas supply
device configured to supply a gas to a vicinity of the probe needle
through an inside or a vicinity of the contact plate in order to
form an atmosphere of a pressure higher than an atmospheric
pressure in the vicinity of the probe needle when inspecting the
electrical characteristic of the power device.
In the present example embodiment, the same effects are achieved as
the above example embodiment. Further, the contact plate is
disposed between the mounting table and the probe card to achieve
the electric conduction between the tester and the electrode on the
rear surface of the power device of which electrical
characteristics is inspected on the semiconductor wafer, and the
contact plate also serves as the surrounding member which forms the
surrounding space. Thus, it is possible to improve simplicity and
efficiency of the spark preventing device.
In accordance with the probe apparatus of the example embodiments,
by using the aforementioned configurations and operations, it may
be possible to suppress the spark (electric discharge) from
occurring near the surface of the wafer simply and efficiently when
inspecting the electrical characteristics of the semiconductor
device at wafer level.
The foregoing summary is illustrative only and is not intended to
be in any way limiting. In addition to the illustrative aspects,
embodiments, and features described above, further aspects,
embodiments, and features will become apparent by reference to the
drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description that follows, embodiments are described
as illustrations only since various changes and modifications will
become apparent to those skilled in the art from the following
detailed description. The use of the same reference numbers in
different figures indicates similar or identical items.
FIG. 1 is partially cross sectional front view illustrating a
configuration of a probe apparatus in accordance with a first
example embodiment;
FIG. 2 is a perspective view of major components of the probe
apparatus seen from obliquely below;
FIG. 3A is a substantially plane view illustrating a positional
relationship between a contact plate and a contactor when a
mounting table and the contactor are located at a central reference
position;
FIG. 3B is a substantially plane view illustrating a positional
relationship between the contact plate and the contactor when the
mounting table and the contactor are maximally shifted in -X
direction;
FIG. 3C is a substantially plane view illustrating a positional
relationship between the contact plate and the contactor when the
mounting table and the contactor are maximally shifted in +X
direction;
FIG. 3D is a substantially plane view illustrating a positional
relationship between the contact plate and the contactor when the
mounting table and the contactor are maximally shifted in +Y
direction;
FIG. 3E is a substantially plane view illustrating a positional
relationship between the contact plate and the contactor when the
mounting table and the contactor are maximally shifted in -Y
direction;
FIG. 4 is a substantially plane view illustrating a region where
the contactor comes into contact with the contact plate when
inspecting all chips;
FIG. 5A is a diagram illustrating an example layout of a plate path
formed in the contact plate in accordance with the example
embodiment;
FIG. 5B is a diagram illustrating another example layout of the
plate path;
FIG. 7 is a partially cross sectional front view illustrating a
configuration of a probe apparatus including a second example of a
spark preventing device;
FIG. 8 is a partially cross sectional front view illustrating a
configuration of a probe apparatus including a third example of the
spark preventing device;
FIG. 9 is a partially cross sectional front view illustrating a
configuration of a probe apparatus including a fourth example of
the spark preventing device;
FIG. 10A is a substantially plane view illustrating a positional
relationship between an opening of the contact plate and an annular
protrusion in accordance with the fourth example thereof;
FIG. 10B is a substantially plane view illustrating a positional
relationship between the opening of the contact plate and the
annular protrusion in accordance with the fourth example
thereof;
FIG. 11 is a cross sectional view illustrating a configuration of a
probe apparatus in accordance with a second example embodiment;
FIG. 12A is a substantially plane view illustrating a modification
example of a surrounding member;
FIG. 12B is a substantially plane view illustrating another
modification example of a surrounding member;
FIG. 13 is a cross sectional view illustrating a configuration of a
probe apparatus in accordance with a third example embodiment;
FIG. 14 is a cross sectional view illustrating a configuration of
major components of a probe apparatus including the fifth example
of a spark preventing device;
FIG. 15 is a bottom view of a contact plate in the probe apparatus
of FIG. 14 seen from below the contact plate;
FIG. 16 is a top view of a mounting table and a semiconductor wafer
in the probe apparatus of FIG. 14 seen from above;
FIG. 17 is a side view for describing an operation of a seal ring
in this example; and
FIG. 18 is a top view for describing the operation of the seal ring
in this example.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the
accompanying drawings, which form a part of the description. In the
drawings, similar symbols typically identify similar components,
unless context dictates otherwise. Furthermore, unless otherwise
noted, the description of each successive drawing may reference
features from one or more of the previous drawings to provide
clearer context and a more substantive explanation of the current
example embodiment. Still, the example embodiments described in the
detailed description, drawings, and claims are not meant to be
limiting. Other embodiments may be utilized, and other changes may
be made, without departing from the spirit or scope of the subject
matter presented herein. It will be readily understood that the
aspects of the present disclosure, as generally described herein
and illustrated in the drawings, may be arranged, substituted,
combined, separated, and designed in a wide variety of different
configurations, all of which are explicitly contemplated
herein.
(Overall Configuration and Operation of Probe Apparatus)
FIG. 1 illustrates a configuration of a probe apparatus in
accordance with a first example embodiment, and FIG. 2 illustrates
a configuration of major components of the probe apparatus seen
from obliquely below.
This probe apparatus is configured to inspect a semiconductor wafer
W on which a pre-process of a semiconductor process has been
performed. Specifically, the probe apparatus is configured to
inspect electrical characteristics (dynamic characteristics, static
characteristics) of respective chips at wafer level on a multiple
number of power devices (e.g., power MOSFETs) that are formed on
the semiconductor wafer W and have electrodes formed on both sides
thereof, i.e., formed on both sides of the wafer W. Typically, the
semiconductor wafer W may be a SiC wafer or a Si wafer, though the
kind of the semiconductor wafer W may not be particularly
limited.
The probe apparatus includes, within a probe chamber 10 provided in
the vicinity of a tester body (not shown) and formed of a
cylindrical body (not shown), a mounting table (chuck top) 12
placed on a moving stage 14; and a probe card 16 provided above the
mounting table 12 and horizontally supported (fastened) by a probe
card holder 18. A test head 20 of the tester is configured to dock
on the probe card 16 and the probe card holder 18 in a detachable
manner.
To elaborate, the mounting table 12 includes a mounting surface on
which the semiconductor wafer W as the inspection target object is
horizontally mounted. The mounting surface is made of a
plate-shaped or film-shaped conductor having high conductivity,
i.e., a mounting surface conductor 22. If the semiconductor wafer W
is mounted on the mounting surface conductor 22, electrodes (drain
electrodes) exposed on a rear surface of the semiconductor wafer W
at a chip unit are brought into direct contact with and
electrically connected with the mounting surface conductor 22.
The mounting table 12 is connected to a vacuum device (not shown)
configured to attract and hold the semiconductor wafer W on the
mounting surface conductor 22. The mounting surface conductor 22
has a multiple number of holes or grooves for vacuum attraction.
Further, the mounting surface conductor 22 is also provided with
holes through which a multiplicity of lift pins (not shown) are
moved up and down to load or unload the semiconductor wafer W on
the mounting table 12.
The moving stage 14 is configured to move the mounting table 12 in
a horizontal (XY) direction, a vertical (Z) direction and a
rotating (.theta.) direction. Further, the moving stage 14 is also
configured to fix (stopping) the mounting table 12 at a certain
position within a moving range.
The probe card 16 is manufactured as one kind of printed circuit
board, and includes one or more probe needles 24G and 24S to be
brought into contact with electrodes (gate electrodes, source
electrodes) exposed on a front surface of the semiconductor wafer W
at a chip unit individually or in common. To be more specifically,
base ends or base portions of the probe needles 24G and 24S are
bonded to lower ends of corresponding connection conductors 26G and
26S of the probe card 16, respectively. Further, middle portions of
the probe needles 24G and 24S are supported by an insulating
supporting member 28 protruded from a bottom surface of the probe
card 16, and leading ends (free ends) of the probe needles 24G and
24S are brought into contact with the corresponding electrodes
(gate electrodes, source electrodes) exposed on the front surface
of the semiconductor wafer W.
The connection conductors 26G and 26S are vertically inserted into
through holes 30G and 30S of the probe card 16, and exposed or
protruded above and below the probe card 16, respectively. As shown
in the drawing, in a docking state, upper ends or top surfaces of
the connection conductors 26G and 26S are brought into direct
electric contact with corresponding terminals 32G and 32S of the
test head 20, respectively. Here, in order to achieve stable
electric connection between the test head 20 and the probe card 16
in the docking state, it may be possible, for example, to provide
springs (not shown) on the side of the terminals 32G and 32S of the
test head 20.
The probe card holder 18 is a strong metal plate and forms a top
surface of the probe chamber 10. The probe card holder 18 is
horizontally extended around the probe card 16 to surround the
probe card 16. The probe card 16 is detachably or replaceably
fastened in an opening formed in a central portion of the probe
card holder 18.
The probe card holder 18 is configured to support a conductive
contact plate 34 while spaced apart from a bottom surface of the
probe card holder 18. In this example embodiment, the contact plate
34 is a single body having, at a central portion thereof, an
opening 25 surrounding the probe needles 24G and 24S of the probe
card 16. The contact plate 34 is horizontally placed between the
probe card holder 18 and the mounting table 12. Insulating bolts 36
are inserted into through holes of the probe card holder 18 from
above. By screwing leading ends of the bolts 36 into screw holes of
the contact plate 34, the contact plate 34 is horizontally
held.
A pair of plate top surface terminals 38 is provided at left and
right (point-symmetric) positions on the top surface of the contact
plate 34. Each plate top surface terminal 38 is electrically
connected to a lower end of a rod-shaped (or block-shaped)
connection conductor 40, which is vertically extended directly
above the plate top surface terminal 38, in direct contact or by
soldering. The connection conductor 40 is inserted into a through
hole 42 of the probe card holder 18, and exposed or protruded on
the probe card holder 18. As depicted in FIG. 1, in the docking
state with the test head 20, an upper end or a top surface of the
connection conductor 40 is electrically connected to a
corresponding terminal 32D of the test head 20 in direct
contact.
For example, in order to achieve stable electric connection in the
docking state, it may be possible to provide a spring (not shown)
on the side of the terminal 32D of the test head 20. Further, a
conductive sleeve or a packing (not shown) may be inserted into the
through hole 42 to allow the connection conductor 40 to be
supported by the probe card holder 18. Further, the pair of left
and right terminals 32D of the test head 20 corresponding to the
left and right plate top surface terminals 38 of the contact plate
34 are electrically connected in common in the test head 20.
A pair of contactors 44 capable of being independently brought into
contact with a bottom surface of the contact plate 34 is provided
at left and right (point-symmetric) positions on a side surface of
the mounting table 12. At any position of the mounting table 12
within its moving range, if one of the contactors 44 is moved
upward (reciprocating) from an original position to a certain
height position, an upper end or a top surface of that contactor 44
may be come into contact with the bottom surface of the facing
contact plate 34.
In this example embodiment, each contactor 44 is implemented by,
but not limited to, a probe pin. Further, there is provided an
elevating device 45 capable of controlling a vertical movement and
a vertical position of the contactor 44 independently from the
moving stage 14. Further, it may be possible to provide a spring
(not shown) at the contactor 44 in order to achieve stable electric
connection between the contactor 44 and the contact plate 34. Each
contactor 44 is electrically connected to the mounting surface
conductor 22 via a flexible connection conductor, e.g., a hard wire
46, which is extended outward from a peripheral edge of the
mounting table 12.
A dynamic characteristic of each chip (power device) on the
semiconductor wafer W is inspected in this probe apparatus as
follows. The test head 20 of the tester is in a docking state as
depicted in FIG. 1, the semiconductor wafer W is downwardly spaced
apart from the leading ends of the probe needles 24G and 24S, and
the contactors 44 are also downwardly spaced apart from the contact
plate 34. In this state, alignment of an inspection target chip
(power device) on the semiconductor wafer W to the probe card 16 or
the probe needles 24G and 24S is performed. For the alignment, by
moving the mounting table 12 on the moving stage 14 in the
horizontal (XY) direction, the electrodes (the gate electrode and
the source electrode) on the front surface of the inspection target
chip are located directly under the leading ends of the
corresponding probe needles 24G and 24S.
Subsequently, the mounting table 12 is moved vertically upward by a
certain stroke, the electrodes (the gate electrodes and the source
electrode) on the front surface of the inspection target chip press
against the corresponding probe needles 24G and 24S from below.
Accordingly, electric conduction is achieved between the electrodes
(the gate electrode and the source electrode) on the front surface
of the inspection target chip and the corresponding terminals 32G
and 32S of the test head 20 via a first measurement line, which
includes the connection conductors 26G and 26S and the probe
needles 24G and 24S of the probe card 16.
Meanwhile, by moving upward (reciprocating) either one of the left
and right contactors 44, the upper end or the top surface of that
contactor 44 is bought into contact with the bottom surface of the
contact plate 34. Accordingly, electric conduction is achieved
between an electrode (drain electrode) on a rear surface of the
inspection target chip and the corresponding terminal 32D of the
test head 20 via a second measurement line, which includes the
mounting surface conductor 22 of the mounting table 12, one of the
hard wire 46, the corresponding one contactor 44, the contact plate
34 and the corresponding one connection conductor 40.
As stated above, the electric conduction is achieved between the
respective electrodes (the gate electrode, the source electrode and
the drain electrode) of the inspection target chip, i.e., the power
device on the semiconductor wafer W and the corresponding terminals
32G, 32S and 32D of the test head 20. In this state, if a preset
voltage is applied between the source electrode and the drain
electrode of the power device from the tester through the first
measurement line and the second measurement line and a preset
control pulse is applied to the gate electrode, a pulse of a
current is outputted from the power device, and the pulse of the
current is sent to the tester through the first measurement line
and the second measurement line. The tester evaluates a dynamic
characteristic by measuring, for example, a turn-on or turn-off
time or a starting or ending time through signal processing based
on the pulse introduced through the terminal 32D of the test head
20, and then determines the faults of the power device.
In this probe apparatus, besides the above-described inspection of
the dynamic characteristic, inspection of a static characteristic
such as a breakdown voltage test can be performed in the same way
as described above excepting that a voltage or a control signal
applied from the tester is different.
FIG. 3A to FIG. 3E show positional relationship between the contact
plate 34 and the contactor 44 when the mounting table 12 and the
contactor 44 are located at a central reference position within a
moving range and when the mounting table 12 and the contactor 44
are maximally shifted in any one direction in case of performing
the above-described inspection of electrical characteristics on all
chips on the semiconductor wafer W. In the shown example, three
contactors 44 are provided in parallel in order to increase a
current capacity.
FIG. 3A illustrates a case where the mounting table 12 is located
at a central position or a reference position (0, 0) in the XY
direction in order to inspect a chip at the center of the
semiconductor wafer W. In this case, the left and right contactors
44 are both located under the contact plate 34. At this position,
as each contactor 44 is moved upward (reciprocating) from an
original position thereof, each contactor may come into contact
with the bottom surface of the contact plate 34. Typically, one of
the left and right contactors 44 is moved upward (reciprocating)
from the original position thereof to be brought into contact with
the bottom surface of the contact plate 34, whereas the other
contactor 44 is stopped at the original position thereof.
Accordingly, the second measurement line may be connected at either
one of the left system and the right system.
FIG. 3B illustrates a case where the mounting table 12 is shifted
from the central position (0, 0) in the XY direction by about D/2
(D denotes a diameter of the wafer) in a -X direction in order to
inspect a chip on a right end of the semiconductor wafer W in the
drawing. In this case, since the left contactor 44 is located at
the left of (outside) the left end of the contact plate 34,
electric contact between the contactor 44 and the contact plate 34
is not made. Since, however, the right contactor 44 is located
under the contact plate 34, electric contact therebetween is
achieved. Accordingly, the second measurement line is connected at
the right system.
FIG. 3C illustrates a case where the mounting table 12 is shifted
from the central position (0, 0) in the XY direction by about D/2
in a +X direction in order to inspect a chip on a left end of the
semiconductor wafer W in the drawing. In this case, reverse to the
case of FIG. 3B, the second measurement line is connected at the
left system.
FIG. 3D illustrates a case where the mounting table 12 is shifted
from the central position (0, 0) in the XY direction by about D/2
in +Y direction in order to inspect a chip on a lower end of the
semiconductor wafer W in this drawing. Further, FIG. 3E illustrates
a case where the mounting table 12 is shifted from the central
position (0, 0) in the XY direction by about D/2 in a -Y direction
in order to inspect a chip on a upper end of the semiconductor
wafer W in this drawing. In both these cases, the second
measurement line is connected at either one of the left system and
the right system.
FIG. 4 shows regions CE where the left and right contactors 44 come
into contact with the contact plate 34 when moving the mounting
table 12 in order to inspect all chips. The regions CE are shaded.
As shown in the drawing, the regions CE forms semicircular arcs on
the left and right sides of the contact plate 34, respectively,
with a central portion of the contact plate 34 therebetween. A size
or an area of the contact plate 34 is shown in minimum in case that
the shape of the plate is a rectangle.
In this probe apparatus, the first measurement line and the second
measurement line for making the electric conduction state between
each electrode of the inspection target power device and each
corresponding terminal of the test head 20 are set to be as short
as possible. Especially, in case of the first measurement line, the
base ends of the probe needles 24G, 24S and the corresponding
terminals 32G, 32S of the test head 20 are arranged to directly
face each other in the vertical direction, and thus, are
electrically connected at a shortest distance via the connection
conductors 26G and 26S of the probe card 16. Further, in case of
the second measurement line, the plate top surface terminal 38 of
the contact plate 34 and the corresponding terminal 32D of the test
head 20 are also arranged to directly face each other in the
vertical direction, and thus, are electrically connected at a
shortest distance via the rod-shaped (or block-shaped) connection
conductor 40 inserted into the through hole 42 of the probe card
holder 18 in an electrically non-contact manner. In this way, by
minimizing the lengths of the first and second measurement lines,
it may be possible to greatly reduce impedance on a pulse current
flowing in the first and second measurement lines when inspecting
the dynamic characteristics of the power device, as compared to the
conventional probe apparatus.
Further, the probe apparatus includes a spark preventing device 50.
The spark preventing device 50 is configured to suppress a spark
(electric discharge) from occurring near the surface of the
semiconductor wafer W by forming an atmosphere of a preset pressure
higher than the atmospheric pressure in the vicinity of the probe
needles 24G and 24S when the above-described inspection of the
electrical characteristics is performed on the inspection target
chip (power device) on the semiconductor wafer W.
The spark preventing device 50 is based on a so-called Paschen's
law. By way of example, as for a SiC wafer, a chip size of a power
device may be, e.g., about several mm.times.several mm; a minimum
distance d.sub.a between the high-voltage probe needle 24S to be
brought into contact with the source electrode and the low-voltage
probe needle 24G to be brought into contact with the gate electrode
may be within, e.g., about several mm; and a minimum distance
d.sub.b between the high-voltage probe needle 24S and an electrode
on an adjacent chip may be within, e.g., several mm.
According to Paschen's law, if the pressure in the vicinity of the
probe needles 24S and 24G is set to p, a voltage (electric
discharge starting voltage) V.sub.a (V.sub.b) when a spark occurs
between two conductors spaced apart from each other at the distance
d.sub.a (d.sub.b) is defined as p*d.sub.a (p*d.sub.b), which is a
product of the pressure p and the distance d.sub.a (d.sub.b), and
there exists a minimum value V.sub.am (V.sub.bm). Typically, the
minimum values V.sub.am and V.sub.bm exist within a depressurized
range lower than the atmospheric pressure.
According to Paschen curve, in a pressure range higher than or
equal to the atmospheric pressure, as the pressure p in the
vicinity of the probe needles 24S and 24G is increased, the
electric discharge starting voltage V.sub.a (V.sub.b) in the
vicinity of the leading end of the high-voltage probe needle 24S or
in the vicinity of the surface of the semiconductor wafer W may
also be increased. Accordingly, it may be difficult for the spark
to occur in the vicinity of the probe needles 24S and 24G or in the
vicinity of the semiconductor wafer W.
The spark preventing device 50 mounted in the probe apparatus
according to the present example embodiment includes a surrounding
member 52 which surrounds the probe needles 24S and 24G between the
probe card 16 and the mounting table 12; and a gas supply device 54
configured to supply a gas to the vicinity of the probe needles 24S
and 24G through the inside or the vicinity of the surrounding
member 52 to form the atmosphere of the preset pressure higher than
the atmospheric pressure in the vicinity of the probe needles 24S
and 24G when inspecting the electrical characteristics of each chip
(power device) on the semiconductor wafer W. In the first example
embodiment shown in FIG. 1 and FIG. 2, the contact plate 34 also
serves as the surrounding member 52.
(First Example of Spark Preventing Device)
As shown in FIG. 1 and FIG. 2, the contact plate 34 is provided
between the probe card holder 18 and the mounting table 12, and has
the opening or an inner peripheral wall 25 surrounding the probe
needles 24G and 24S of the probe card 16 at a central portion
thereof. This contact plate 34 serves as the surrounding member 52
in accordance with the first example. Here, an endless sealing
member, e.g., an O-ring 53 is inserted in a gap between the contact
plate 34 and the probe card holder 18 (or the probe card 16) to be
located closer to a central position than the plate top surface
terminals 38. With this configuration, a partitioned space or
surrounding space 35 for inspection confined by the probe card 16,
the probe card holder 18, the contact plate 34, the semiconductor
wafer W and the mounting table 12 is formed in the vicinity of the
probe needles 24G and 24S.
The gas supply device 54 includes a gas supply source 56 provided
outside the probe chamber 10; gas discharge opening 58 formed in or
near an inner peripheral surface 34a of the contact plate 34 facing
the probe needles 24G and 24S; and a gas supply line 60 connecting
the gas supply source 56 and the gas discharge opening 58; and an
opening/closing valve 62 provided at the gas supply line 60.
The gas supply source 56 includes a tank that stores a gas for
forming a positive pressure atmosphere in the vicinity of the probe
needles 24G and 24S; a compressor or gas supply pump configured to
discharge a positive pressure gas from the tank; and a regulator
configured to control a pressure of the positive pressure gas
discharged from the gas supply pump.
In this example, the gas discharge opening 58 may be plural in
numbers at the inner peripheral surface 34a of the contact plate 34
with a uniform density, desirably. The gas supply line 60 includes
a relay line 64 connected to a through hole 57 of the probe card
holder 18; an external pipeline 66 extended from an outlet of the
gas supply source 56 to an inlet (upper end) of the relay line 64;
and a plate path 68 extended from an outlet (lower end) of the
relay line 64 to the gas discharge openings 58 through the contact
plate 34.
In the gas supply device 54, if the opening/closing valve 62 is
opened, the positive pressure gas discharged from the gas supply
source 56 at the preset pressure is flown through the gas supply
line 60, discharged from the gas discharge openings 58 formed in
the inner peripheral surface 34a of the contact plate 34 and
supplied into the surrounding space 35. A top portion of the
surrounding space 35 is completely closed by the probe card 16, the
probe card holder 18, the contact plate 34 and the O-ring 53.
Meanwhile, a gap g of, e.g., about 0.8 mm is formed between the
contact plate 34 and the semiconductor wafer W or the mounting
table 12 in a bottom portion of the surrounding space 35.
Accordingly, the positive pressure gas supplied into the
surrounding space 35 is filled in the surrounding space 35 and
leaked to the outside from the gap g at the bottom of the
surrounding space 35. Here, by setting the pressure or the flow
rate of the positive pressure gas supplied into the surrounding
space 35 from the gas supply device 54 to be sufficiently high, it
may be possible to form the preset pressure atmosphere higher than
the atmospheric pressure in the vicinity of the probe needles 24G
and 24S.
As stated above, in the surrounding space 35 accommodating the
probe needles 24S and 24G therein, as the pressure p is increased,
a spark (electric discharge) starting voltage is also increased in
the vicinity of the surface of the semiconductor wafer W (more
accurately, in the vicinity of the leading end of the high-voltage
probe needle 24S), according to Paschen curve. Accordingly, the
pressure p within the surrounding space 35 needs to be adjusted
such that a voltage applied to each chip (power device) on the
semiconductor wafer W is below the electric discharge starting
voltage within the surrounding space 35. As a result, it is
possible to suppress a spark from occurring near the probe needles
24S and 24G or near the surface of the semiconductor wafer W. In
general, the pressure p within the surrounding space 35 may be
adjusted within a pressure range of about 1 atm<p<about 10
atm.
The present inventors conducted a breakdown voltage test for a
power device formed on a SiC wafer by using the above-described
probe apparatus. When the pressure p within the surrounding space
35 is regulated to, e.g., about 6 atm by using dry air as a
positive pressure gas, no spark was observed even at a test voltage
of, e.g., about 7000 V.
FIG. 5A illustrates an example layout of the plate path 68 formed
in the contact plate 34. As shown in this drawing, the plate path
68 includes a single level or multiple level (two level in the
shown example) manifold paths 70 and 72 extended around the opening
25; communication paths 74 extended in a radial shape to connect
the outer manifold path 70 and the inner manifold path 72; nozzle
paths 76 extended in a radial shape to connect the inner manifold
path 72 and the gas discharge openings 58. In this layout of the
plate path 68 for a gas flow, it may be possible to discharge the
positive pressure gas uniformly from the entire circumference of
the opening 25, i.e., from the inner peripheral surfaces 34a along
the entire circumference (four sides) of the contact plate 34.
Here, the layout shown in FIG. 5A is nothing more than an example,
and various other layouts of the plate path 68 may be adopted. By
way of example, as depicted in FIG. 5B, the contact plate 34 and
the opening 25 may have circular shapes in a plane view. In this
case, the outer and/or the inner manifold path 70 and 72 may be
formed in circular ring shapes. Further, as for the gas discharge
openings 58, the positive pressure gas may not necessarily be
discharged from the entire circumference of the opening 25 but may
be discharged from a part of the inner peripheral surfaces 34a of
the contact plate 34, for example, from two opposite sides or from
a single side thereof.
Further, the contact plate 34 may be made of a conductor having
high conductivity and rigidity. The contact plate 34 may not be
limited to a single-layered plate, but it may be a multilayered
plate such as a laminated metal plate. Further, the shape of the
plate path 68 may not be limited to the above-described tunnel
shape formed within the contact plate 34, but the plate path 68 may
have various shapes, such as a groove shape formed on a surface of
the contact plate 34 and equipped with a sealing cover, a pipe
shape extended along the surface of the contact plate 34, etc.
Although the gas supply device 54 may have the single gas supply
source 56 configured to discharge a single kind of positive
pressure gas, it may be desirable that the gas supply device 54
includes multiple kinds of positive gas supply sources, e.g., a dry
air supply source 56(1), a nitrogen gas supply source 56(2) and an
insulating gas supply source 56(3).
In such a configuration, one of the gas supply sources 56(1), 56(2)
and 56(3) may be selectively used by controlling opening/closing
valves 57(1), 57(2) and 57(3) of output ports thereof depending on
inspection conditions of electrical characteristics performed in
the probe apparatus (e.g., the kind of a semiconductor wafer W, the
kind of a power device, the kind of the inspection, a test voltage
applied to the power device, etc.). By way of example, when the
test voltage applied to the power device is not so high, e.g.,
about 1000 V or less, the dry air supply source 56(1) or the
nitrogen gas supply source 56(2) may be used at first. Meanwhile,
if the test voltage is considerably high, e.g., about 3000 V or
more, the insulating gas supply source 56(3) may be used at
first.
The insulating gas supply source 56(3) is configured to discharge a
commonly known insulating gas such as, but not limited to,
SF.sub.6, at a preset pressure. Further, the insulating gas supply
source 56(3) may include an insulating liquid vaporizing device
configured to vaporize an insulating liquid having a higher voltage
resistance, e.g., Fluorinert (registerted trademark, produced by 3M
company) by a bubbling method such as a nitrogen bubbling method to
generate a nitrogen-mixed insulating gas.
In this example, the gas supply line 60 connecting the gas supply
source 56 and the surrounding space 35 passes through the vicinity
of the probe card 16, i.e., through the probe card holder 18.
Accordingly, the gas supply line 60 may not affect design,
manufacture, structure or replacement/installation of the probe
card 16 at all.
In this example, the spark preventing device 50 suppresses a spark
from occurring on the surface of the semiconductor wafer W based on
Paschen's Law by forming the atmosphere of the preset pressure
atmosphere higher than the atmospheric pressure in the vicinity of
the probe needles 24S and 24G. Thus, unlike in the conventional
technique of supplying the insulating liquid on the semiconductor
wafer as the inspection target object, the spark preventing device
50 has a simple configuration and can be simply controlled, without
increasing the inspection time.
Further, in this example, as a part or a section of the second
measurement line for achieving electric conduction between the
tester and the electrode on a rear surface of the power device of
which electrical characteristics would be inspected on the
semiconductor wafer, the contact plate 34 is disposed between the
mounting table 12 and the probe card 16 or the probe card holder
18. This contact plate 34 also serves as the surrounding member 52,
which forms, as a constituent component of the spark preventing
device 50, the surrounding space 35 by surrounding the vicinity of
the probe needles 24S and 24G. This configuration may greatly
contribute to simplicity and efficiency of the entire probe
apparatus as well as those of the spark preventing device 50.
(Second Example of Spark Preventing Device)
FIG. 7 illustrates a second example of the spark preventing device
50. In the spark preventing device 50 of the second example, the
gas supply device 54 of the first example is partially modified.
The spark preventing device 50 of the second example has a
structure capable of increasing a pressure of a positive pressure
atmosphere within the surrounding space 35.
To elaborate, the gas discharge openings 58 for discharging a
positive pressure gas into the surrounding space 35 are formed not
only in the inner peripheral surfaces 34a of the contact plate 34
but also in a top surface and a bottom surface of the contact plate
34 in the vicinity of the inner peripheral surfaces 34a. With this
configuration, a total opening area of the gas discharge openings
58 is increased and, thus, the conductance can be lowered. Further,
a dual system of gas supply sources 56A and 56B and gas supply
lines 60A and 60B is provided, and a flow rate of the positive
pressure gas supplied into the surrounding space 35 can be
increased as required.
Further, in this second example, the positive pressure gas is
discharged into the gap g between the contact plate 34 and the
semiconductor wafer W or the mounting table 12 from the gas
discharge openings in the bottom surface of the contact plate 34,
so that air curtain may be formed in the gap g. Accordingly, it may
be possible to suppress the positive pressure gas filled in the
surrounding space 35 from leaking to the outside through the gap g.
Thus, a pressure within the surrounding space 35 can be easily
adjusted to a required high pressure (e.g., about 6 atm).
Further, the second gas supply source 56B may be omitted, and the
first gas supply source 56A may be connected to and shared by the
two gas supply lines 60A and 60B.
(Third Example of Spark Preventing Device)
FIG. 8 illustrates a third example of the spark preventing device
50. The spark preventing device 50 of the third example includes,
in addition to the configuration of the first example or the second
example, a gas collecting device 78 configured to collect, by a
vacuum attracting force, the positive pressure gas supplied to the
vicinity of the probe needles 24G and 24S (i.e., the surrounding
space 35) by the gas supply device 54.
In the shown configuration example, a vacuum source 82 and the
second gas supply source 56B are connected to the second gas supply
line 60B of the gas supply device 54 in parallel via the switching
valve 80. In this configuration, when the vacuum source 82 is
connected to the gas supply line 60B via the opening/closing valve
83 and the switching valve 80, the gas discharge openings 58 in the
bottom surface of the contact plate 34 may serve as suction
openings, and the second gas supply line 60B serves as an exhaust
line 86.
In this configuration, the positive pressure gas that is leaked
from the surrounding space 35 to the outside via the gap g is
suctioned into the suction openings 84, and then, is returned back
to the vacuum source 82 via the exhaust line 86 and the switching
valve 80.
The gas collecting device 78 in this example may be appropriately
used, for example, when it is undesirable that the positive
pressure gas (especially, the insulating gas), which is supplied
into the surrounding space 35 from the first gas supply source 56A
and the gas supply line 60A, is diffused to the vicinity
thereof.
Further, the second gas supply source 56B and the switching valve
80 may be omitted, and the vacuum source 82 may be connected to an
exclusive exhaust line 86 via the opening/closing valve 83.
(Fourth Example of Spark Preventing Device)
FIG. 9 illustrates a modification example of the contact plate 34
and a fourth example of the spark preventing device 50.
In a probe apparatus shown in FIG. 9, the size or the area of a
contact plate 34 is increased such that both of the left and right
contactors 44 can be brought into contact with a bottom surface of
the contact plate 34 by being moved upward to the reciprocating
positions wherever the mounting table 12 and the contactors 44 are
located within their moving ranges when inspecting all chips (power
devices) on the semiconductor wafer W as the inspection target
object. That is, the size or the area of the contact plate 34 is
increased such that the second measurement lines are connected in
parallel at both of the left and right systems.
Further, in this probe apparatus, an annular protrusion 90 made of
an insulator such as, but not limited to, a resin is provided to
have a preset height (protrusion amount) at a position close to the
top surface of the mounting table 12, desirably, at a position
close to an edge portion of the top surface of the mounting table
12. The annular protrusion 90 is one of the constituent components
of the spark preventing device 50.
As shown in FIG. 9, in order to inspect electrical characteristics
of a certain chip (power device) on the semiconductor wafer W, when
the electrodes (the gate electrode and the source electrode) on the
front surface of the inspection target chip are in contact with the
leading ends of corresponding probe needles 24G and 24S,
respectively, a top portion of the annular protrusion 90 is in
contact with or located adjacent to the bottom surface of the
contact plate 34. As a result, the gap g between the contact plate
34 and the mounting table 12 is closed to isolate at least an
atmosphere therein from the outside. In such a case, as shown in
FIG. 10A and FIG. 10B, wherever the mounting table 12 and the
contactor 44 are located within their moving ranges, the annular
protrusion 90 is allowed to be located outside an opening 25 of the
contact plate 34, i.e., outside (around) the surrounding space
35.
In this configuration, since the atmosphere within the surrounding
space 35 is isolated from the outside by the annular protrusion 90,
it may be possible to increase a pressure of a positive pressure
atmosphere within the surrounding space 35 by the gas supplied from
the gas supply device 54.
Further, in the fourth example, the gas collecting device 78 in the
third example may also be employed. In that configuration, it may
be possible to perform a pressure control of increasing or
decreasing the pressure within the surrounding space 35 more
efficiently at a high speed.
Other Example Embodiments or Modification Examples
FIG. 11 illustrates a configuration of a probe apparatus in
accordance with a second example embodiment. Like the probe
apparatus in the above-described first example embodiment, the
probe apparatus of the second example embodiment is also configured
to inspect electrical characteristics (dynamic characteristics and
static characteristics) of a multiple number of power devices, each
of which is formed on a semiconductor wafer W and has electrodes on
both sides of a chip, i.e., on both sides of the wafer. The probe
apparatus inspects every chip at wafer level.
In this second example embodiment, however, the contact plate 34
(FIG. 1) is not used (accordingly, the contactors 44 and the
connection conductor 40 are not used) as a second measurement line
for achieving electric conduction between a rear surface electrode
of an inspection target power device and a tester. Instead, the
probe apparatus of the second example embodiment adopts a
configuration in which an electric cable 92 is routed from a
mounting surface conductor 22 of a mounting table 12 to a
corresponding terminal 32C of a test head 20. Both ends of the
electric cable 92 are connected to the mounting surface conductor
22 and the terminal 32C via connectors 94 and 96, respectively.
In this second example embodiment, the contact plate is not used as
the second measurement line, but an insulating plate 98 made of,
but not limited to, a resin may be used as the surrounding member
52. In this configuration, the insulating plate 98 may be directly
fastened to the probe card holder 18, and the O-ring 53 (FIG. 1)
may be omitted.
In the probe apparatus of this second example embodiment, a
configuration and an operation of a spark preventing device 50 are
the same as those of the first to fourth examples thereof. Further,
in case of providing an annular protrusion 90 (FIG. 9) in the spark
preventing device 50, the annular protrusion 90 may be provided at
the insulating plate 98.
Further, as another modification example of the surrounding member
52, the contact plate 34 may be divided (split) into a pair of left
and right plates 34A and 34B, and an insulating plate 100 may be
provided therebetween, as shown in FIG. 12A and FIG. 12B. In this
configuration, a plate path 68 forming a part of the gas supply
line 60 may be formed in the separate contact plates 34A and 34B,
or may be formed in the insulating plate 100.
FIG. 13 illustrates a configuration of a probe apparatus in
accordance with a third example embodiment. This probe apparatus is
configured to inspect electrical characteristics (dynamic
characteristics and static characteristics) of a multiple number of
power devices, each of which is formed on a semiconductor wafer W,
and has electrodes only on a front surface of a chip (without
having an electrode on a rear surface of the chip). The probe
apparatus is configured to inspect every chip at wafer level.
In this configuration, one or more probe needles 24G, 24S and 24D
to be brought into contact with the electrodes (i.e., the gate
electrode, the source electrode and the drain electrode) of each
chip (power device) exposed on a front surface of the semiconductor
wafer W individually or in common are connected to a probe card 16
via connection conductors 26G, 26S and 26D, respectively. As shown
in the drawing, in a docking state, upper ends or top surfaces of
the connection conductors 26G, 26S and 26D are electrically
connected in direct contact with corresponding terminals 32G, 32S
and 32D of a test head 20.
During the inspection, a mounting table 12 is moved upward by a
certain stroke, and the gate electrode, the source electrode and
the drain electrode of the inspection target chip press against
leading ends of the corresponding probe needles 24G, 24S and 24D
from below. Accordingly, electric conduction is achieved between
the gate electrode, the source electrode and the drain electrode of
the inspection target chip and the corresponding terminals 32G, 32S
and 32D of the test head 20.
In this third example embodiment, as in the second example
embodiment, the contact plate 34 is not used as a second
measurement line, but an insulating plate 98 made of, but not
limited to, a resin may be used as a surrounding member 52. A
configuration and an operation of a spark preventing device 50 are
the same as those of the first to fourth examples thereof.
Now, referring to FIG. 14 to FIG. 18, a fifth example of the spark
preventing device 50 will be explained. FIG. 14 illustrates major
components of a probe apparatus including the spark preventing
device 50 of the fifth example. FIG. 15 is a bottom view
illustrating a contact plate 34 in this probe apparatus, seen from
below, and FIG. 16 is a top view illustrating a mounting table 12
and a semiconductor wafer in this probe apparatus, seen from above.
FIG. 17 and FIG. 18 provide a side view and a top view for
describing an operation of a seal ring in this fifth example,
respectively.
In the probe apparatus of this fifth example, an annular or an
endless labyrinth seal 102 is provided on a bottom surface of the
contact plate 34. Desirably, the labyrinth seal 102 may be made of
a metal such as SUS, copper or aluminum, or a heat resistant resin
such as PEEK. The labyrinth seal 102 has a multiple number of
concentric protrusions/recesses or labyrinth fins FN surrounding
leading ends of probe needles 24G and 24S.
Desirably, the labyrinth seal 102 is fastened to an innermost
bottom surface (a bottom surface most adjacent to an inner
peripheral surface 34a) of the contact plate 34 via a partition
wall 104. The partition wall 104 is fixed to or formed as one body
with the bottom surface of the contact plate 34, and is protruded
in a height or thickness of, e.g., several mm. The partition wall
104 is configured to hold the labyrinth seal 102, and also to
adjust a gap between the bottom surface of the contact plate 34 and
a semiconductor wafer W on the mounting table 12 at a position
other than the labyrinth seal 102 is provided. Here, the partition
wall 104 may be omitted, and the labyrinth seal 102 may be directly
bonded to or formed as one body with the bottom surface of the
contact plate 34. A gap .DELTA.g may be formed between the
labyrinth seal 102 and the semiconductor wafer W on the mounting
table 12. The labyrinth seal 102 is one of constituent components
of the spark preventing device 50.
In this probe apparatus, a positive pressure gas flowing from a
surrounding space 35 to the exterior atmospheric space may suffer a
great pressure loss due to the multi-level labyrinth fins FN when
the positive pressure gas passes through the gap .DELTA.g. That is,
a great resistance is applied to the gas flowing from the
high-pressure surrounding space 35 to the low-pressure atmospheric
space meets through a throttling effect at a leading end of each
labyrinth fin FN and a vortex generated between adjacent labyrinth
fins FN. Accordingly, the gas leakage may not occur easily.
Further, the shape and the number of the shown labyrinth fins FN
are nothing more than examples, and the shape and the number of the
labyrinth fins may not be particularly limited as long as they have
an effect of suppressing the gas leakage.
With this configuration, in case that the gap .DELTA.g facing the
labyrinth seal 102 is set to be of a size equivalent to the gap g
between the contact plate 34 and the semiconductor wafer W in the
first example (FIG. 1), a flow rate or a leakage amount of the
positive pressure gas flowing from the surrounding space 35 to the
exterior atmospheric space may be greatly reduced.
Further, if the leakage amount of the positive pressure gas is
same, the gap .DELTA.g in this fifth example can be set to be of a
size several times larger than the size of the gap g in the first
example (FIG. 1). By way of example, even if the gap .DELTA.g is
set to be about 0.4 mm, it may be possible to achieve the same gas
leakage suppressing effect as obtained in case of setting the gap g
to be about 0.1 mm or less in the first example.
In this fifth example, as stated, the gap .DELTA.g facing the
labyrinth seal 102 need not be narrowed extremely. Thus, it may be
possible to appropriately cope with a dimensional tolerance in each
component in the vicinity of the surrounding space 35 or
non-uniformity in positions of the leading ends of the probe
needles.
Further, in this example, an annular or endless seal ring 106 is
provided at a periphery portion of a top surface of the mounting
table 12 to surround the semiconductor wafer W. The seal ring 106
may be made of, but not limited to, a metal such as SUS, copper or
aluminum, or a heat resistant resin such as PEEK. Desirably, the
seal ring 106 has a thickness same as that of the semiconductor
wafer W on the mounting table 12. The seal ring 106 is also one of
constituent components of the spark preventing device 50.
In this probe apparatus, when testing a chip near the edge of the
semiconductor wafer W, the mounting table 12 is maximally shifted
from the central position (0, 0) of the XY direction by about D/2
(D denotes a wafer diameter) in +X or -X direction, or +Y or -Y
direction, as depicted in FIG. 3B to FIG. 3E. In these cases, the
surrounding space 35 or the opening 25 of the contact plate 34 may
be protruded outward from the edge of the semiconductor wafer W in
a radial direction.
In this example, even if the surrounding space 35 or the opening 25
of the contact plate 4 is protruded outward from the edge of the
semiconductor wafer W, the labyrinth seal 102 is not protruded to
the outside of the seal ring 106. Accordingly, the gas leakage
suppressing effect of the labyrinth seal 102 may be fully
exerted.
Precisely, as shown in FIG. 18, an annular gap or groove 110
extended in a circumferential direction is formed between an outer
peripheral surface of the semiconductor wafer W and an inner
peripheral surface of the seal ring 106 on the mounting table 12.
Accordingly, the positive pressure gas may be leaked to the
exterior atmospheric space through the groove 110, though the gas
leakage amount may be small. This gas leakage amount may be very
small, as compared to the gas leakage amount when the seal ring 106
is not provided on the mounting table 12.
As discussed above, in this example, by the configuration and the
operation of the labyrinth seal 102 and the seal ring 106, it may
be possible to reduce a leakage amount of the positive pressure gas
supplied into the surrounding space 35 in which the probe needles
24S and 24G are accommodated. Thus, it may be possible to set or
adjust a pressure within the surrounding space 35 to a required
high pressure.
Furthermore, in this example, by supplying the positive pressure
gas into the surrounding space 35 and a sealed space around it, a
load applied to each component in the vicinity of the surrounding
space 35 may be greatly reduced.
As a comparative example, as in the fourth example (FIG. 9), the
annular protrusion 90 surrounding the semiconductor wafer W on the
mounting table 12 and capable of being brought into contact with
the bottom surface of the contact plate 34 is provided. In this
case, if a diameter of the semiconductor wafer W is, e.g., about 5
inches and a supply pressure of the positive pressure gas is, e.g.,
about 0.6 MPa, a thrust of, e.g., about 760 kg may be generated in
an upward direction or a downward direction in the vicinity of the
surrounding space 35 (thrust=area.times.pressure). Here, the
downward thrust may be a force pushing the mounting table 12
downward, whereas the upward thrust may be a force lifting up the
probe card holder 18 via the contact plate 34 and the probe card
16. For the reason, the probe apparatus needs to have a strong
structure capable of enduring the great thrust in the upward and
downward directions.
Meanwhile, in the fifth example, since the labyrinth seal 102 is
provided on the bottom surface of the contact plate 34, an area of
the positive pressure space in the vicinity of the surrounding
space 35 which generates a thrust may be defined by a diameter of
the labyrinth seal 102, not by the diameter of the semiconductor
wafer W. By way of example, when an inner diameter of the labyrinth
seal 102 is about 20 mm and an outer diameter thereof is about 40
mm, the diameter of the positive pressure space contributing to the
generation of the thrust may be set to be of an average value
(about 30 mm) of the inner diameter and the outer diameter. In this
configuration, in case that a supply pressure of the positive
pressure gas is, e.g., about 0.6 MPa, the thrust in the upward
direction and the downward direction may be as small as about 42
kg. Thus, a force applied to the mounting table 12, the contact
plate 34, the probe card 16, the probe card holder 18, and the like
in the vicinity of the surrounding space 35 may be remarkably
reduced.
From the foregoing, it will be appreciated that various embodiments
of the present disclosure have been described herein for purposes
of illustration, and that various modifications may be made without
departing from the scope and spirit of the present disclosure.
Accordingly, the various embodiments disclosed herein are not
intended to be limiting, with the true scope and spirit being
indicated by the following claims.
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